news: Automake 1.13 will require Autoconf >= 2.65

news: Automake 1.13 will require Autoconf >= 2.65

Autoconf 2.65 is almost three years old now, so requiring it is
acceptable.  Also, the soon-to-appear support for Objective C++
in Automake will be simplified if we can assume that Autoconf
version (which is the one that introduced support for Objective
C++).

* NEWS (Planned future backward-incompatibilities): Automake 1.13
will require Autoconf 2.65 or later.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>